Inside Google, they're roughly the same. You used to refer to them together, they sat next to each other, worked on the same projects as you point out, roughly until Jeff started Brain. Outside of Google, Jeff is more popular probably because he gives all the talks and interviews (plus his legends...). I'm sure Sanjay has presented a few times, but I can't recall any, while Jeff has been everywhere and his slides are linked to all the time, e.g. the latency numbers all engineers should know.